Spark plugs used to ignite gaseous fuel in the combustion chambers of internal combustion engines typically have a gap between the electrode and conductor at one end portion of the spark plug. Such spark plugs are often referred to as "J-gap" type spark plugs. In rich gaseous fuel environments, these spark plugs have proven to be adequate to cause ignition of the fuel and satisfactory engine operation.
Tighter government emission regulations have prompted changes in internal combustion engine designs and operating parameters. In gaseous fueled engines, cleaner burning has been achieved by running the engine on leaner air to gaseous fuel ratio mixtures. Cleaner burning of leaner air to gaseous fuel mixtures after initial combustion has been further enhanced by adding swirl to the combustion chambers inlet air charge. This Swirl, however, induces turbulence near the gap of the "J-gap" spark plug and inhibits initial ignition of the gaseous fuel to air ratio mixture.
It has been known to provide an adapter for a "J-gap " spark plug. An example of such a spark plug is shown in U.S. Pat. No. 4,182,281, to Leo A. Heintzelman, dated Jan. 8, 1980. The adapter is screw threadably connected to the threaded end portion of the spark plug and encloses the open end portion of the spark plug. Such adapters tend to be expensive to manufacture and do not adequately provide the desired ignition characteristics.
The present invention is directed to overcoming one or more of the problems as set forth above.